ABSTRACT
Background & objectives: The epidemiology of dengue fever (DF) is complex in the Indian subcontinent as all the four serotypes are circulating. This study reports observations on dengue cases from a virus diagnostic laboratory of a north Indian tertiary care hospital catering to areas in and around Lucknow, Uttar Pradesh. Methods: Serum samples were obtained from suspected cases of dengue referred to the virus diagnostic laboratory during 2011 to 2013, and detailed history was taken on a pre-structured datasheet. All samples were tested for anti-dengue virus (DV) IgM antibodies and DV-non structural protein 1 antigen (NS1Ag) by ELISA. NS1Ag positive samples were tested further by conventional RT-PCR for DV-RNA detection and serotyping. Results: Of the 4019 suspected patients of dengue, 886 (22%) showed laboratory evidence of dengue virus infection. Of these, 19, 17 and 27 per cent were positive in 2011, 2012 and 2013, respectively. Children and adults were similarly affected by dengue in all the three years. Males were more commonly affected than females. The predominant DV serotype detected was DV-2, DV-1 and DV-3 in 2011, 2012 and 2013, respectively. DV-4 serotype was not detected. About half the cases positive for DV infection, showed symptoms of dengue with warning signs/ severe dengue. A distinct seasonality with increase in number of dengue cases in the post monsoon period was seen. Interpretation & conclusions: Change in circulating serotype of dengue virus; a distinct adult dengue involvement; and a remarkable number of cases presenting with severe dengue manifestations are the main findings of this study.
ABSTRACT
Non structural protein 4 (NSP4) gene of Rotavirus encodes a multifunctional protein which has significant role in viral multiplication and pathogenesis of acute watery diarrhoea associated with rotaviral gastroenteritis. It is known as the first viral enterotoxin and mutations of the gene have been linked to altered pathogenesis. This study was planned to ascertain the genotypes and genetic variations of NSP4 gene in the rotavirus strains prevalent in this area. We collected consecutive diarrhoeal stools from equal no of children aged under five years hospitalized with diarrhoea in a period from January 2010 to June 2012 and tested them for rotavirus antigen by ELISA. NSP4 gene was amplified by RT-PCR and subsequently sequenced (Big-Dye terminator kit using 3130 ABI, Genetic analyzer) and genotyped by Rotavirus C software. Of the 260 samples, 58(22.3%) samples were positive by ELISA. We were able to amplify NSP4 gene by RTPCR from 45 strains of which 35 amplicons were selected for sequencing. Total 25(71.4%) strains belonged to genotype E1, 6 (17.1%) strains to genotype E2 and 4 (11.4%) matched with the genotype E6. Sequence analysis revealed changes in the nucleotides causing punctate mutations in the conserved regions, the Inter species variable domain (ISVD) and the enterotoxin region (amino acid 114-135). On evolutionary analysis of 33 strains amino acid at position 131 was found under positive selection.